Helper class to perform CRUD operations in ASP.Net Web Forms

DatabaseHelper.cs

using System;
using System.Collections.Generic;
using System.Configuration;
using System.Data;
using System.Data.SqlClient;
using System.Linq;
using System.Web;

/// <summary>
/// Summary description for CRUDHelper
/// </summary>
public class DatabaseHelper
{
    private SqlConnection connection;
    private SqlDataAdapter adapter;
    private SqlCommand command;
    private string Query;

    public DatabaseHelper()
    {
        connection = new SqlConnection(ConfigurationManager.ConnectionStrings["conn"].ConnectionString);
    }

    public DatabaseHelper(string ConnectionString)
    {
        connection = new SqlConnection(ConnectionString);
    }

    public DataTable SelectQuery(string Query)
    {
        this.Query = Query;
        command = new SqlCommand(Query, connection);
        return ExecuteQuery();
    }

    public DataTable SelectAnd(string TableName, Dictionary<string, string> Where = null, List<string> OrderBy = null)
    {
        Query = "SELECT * FROM [" + TableName + "]";
        if (Where != null)
        {
            if (Where.Count > 0)
            {
                Query += " WHERE" + GenerateWhere("AND", Where);
            }
        }
        if (OrderBy != null)
        {
            if (OrderBy.Count > 0)
            {
                Query += " ORDER BY" + GenerateOrderBy(OrderBy);
            }
        }

        command = new SqlCommand(Query, connection);
        BindParameters(Where);
        return ExecuteQuery();
    }

    public DataTable SelectOr(string TableName, Dictionary<string, string> Where = null, List<string> OrderBy = null)
    {
        Query = "SELECT * FROM [" + TableName + "]";
        if (Where != null)
        {
            if (Where.Count > 0)
            {
                Query += " WHERE" + GenerateWhere("AND", Where);
            }
        }
        if (OrderBy != null)
        {
            if (OrderBy.Count > 0)
            {
                Query += " ORDER BY" + GenerateOrderBy(OrderBy);
            }
        }

        command = new SqlCommand(Query, connection);
        BindParameters(Where);
        return ExecuteQuery();
    }

    public void Insert(string TableName, Dictionary<string, string> Data)
    {
        Query = "INSERT INTO [" + TableName + "] " + GenerateColumnParameters(false, Data) + " VALUES " + GenerateColumnParameters(true, Data);
        command = new SqlCommand(Query, connection);
        BindParameters(Data);
        ExecuteQuery();
    }

    public void Update(string TableName, Dictionary<string, string> Data, Dictionary<string, string> Where)
    {
        Query = "UPDATE [" + TableName + "] SET " + GenerateUpdateParameters(Data) + " WHERE " + GenerateWhere("AND", Where);
        command = new SqlCommand(Query, connection);
        BindParameters(Data);
        BindParameters(Where);
        ExecuteQuery();
    }

    public void Delete(string TableName, Dictionary<string, string> Where)
    {
        Query = "DELETE FROM [" + TableName + "] WHERE " + GenerateWhere("AND", Where);
        command = new SqlCommand(Query, connection);
        BindParameters(Where);
        ExecuteQuery();
    }

    private string GenerateWhere(string Operator, Dictionary<string, string> Where)
    {
        string WhereClause = "";
        foreach (var item in Where)
        {
            WhereClause += " [" + item.Key + "] = @" + item.Key + " " + Operator;
        }
        WhereClause = WhereClause.Substring(0, WhereClause.Length - (Operator.Length + 1));
        return WhereClause;
    }

    private string GenerateOrderBy(List<string> OrderBy)
    {
        string OrderByClause = "";
        foreach (var item in OrderBy)
        {
            OrderByClause += " " + item + ",";
        }
        OrderByClause = OrderByClause.Substring(0, OrderByClause.Length - 1);
        return OrderByClause;
    }

    private string GenerateUpdateParameters(Dictionary<string, string> Data)
    {
        string UpdateParameters = "";
        foreach (var item in Data)
        {
            UpdateParameters += "[" + item.Key + "] = @" + item.Key + ", ";
        }
        UpdateParameters = UpdateParameters.Substring(0, UpdateParameters.Length - 2);
        return UpdateParameters;
    }

    private string GenerateColumnParameters(bool IsParam, Dictionary<string, string> Data)
    {
        string ColumnParameters = "(";
        foreach (var item in Data)
        {
            if (!IsParam)
            {
                ColumnParameters += "[" + item.Key + "],";
            }
            else
            {
                ColumnParameters += "@" + item.Key + ",";
            }
        }
        ColumnParameters = ColumnParameters.Substring(0, ColumnParameters.Length - 1);
        ColumnParameters += ")";
        return ColumnParameters;
    }

    private DataTable ExecuteQuery()
    {
        DataTable table = new DataTable();
        adapter = new SqlDataAdapter(command);
        adapter.Fill(table);
        return table;
    }

    private void BindParameters(Dictionary<string, string> Parameters)
    {
        if (Parameters != null)
        {
            foreach (var Parameter in Parameters)
            {
                command.Parameters.AddWithValue("@" + Parameter.Key, Parameter.Value);
            }
        }
    }
}